How to list all environment variables in a c/c++ app

I know that when programming in c++ I can access individual environment variables with getenv.

I also know that, in the os x terminal, I can list ALL of the current environment variables using env.

I'm interested in getting a complete list of the environment variables that are available to my running c++ program. Is there a c/c++ function that will list them? In other words, is there a way to call env from my c++ code?